In the SCMLoader version I uploaded today, a new program is available - SCModLoader.exe. Run this while Starcraft is running with SCMLoader to load and unload MPQ archives with the game running.

For those making maps for use with SCMLoader, you can now use this to tell SCMLoader to unload your map so that you are able to edit it directly, without needing to open another map in Starcraft first, close Starcraft first, or use some other workaround.